The typical formats for transmitting and recording compressed music and image data (will be referred to as “A content data” hereunder) include the so-called MPEG-2PS (PS: program stream) file format established as ISO/EEC 13818-1 and MPEG-4 file format established as ISO/IEC 14496-1 (will also be referred to as “MP4” hereunder).
In MPEG-2PS, it is required that AV content data, recording position necessary for reading and output of the AV content data, output-time information, etc. (will be referred to as “reference information” hereunder) should be allocated fragmentally and alternately. In MP4, it is required that compressed AV content information and all reference information should be collected and grouped by genre.
Note that when AV content data is recorded to a recording medium according to either or MPEG-2PS or MP4, there arise the following problems.
When MPEG-2PS is used, AV content data and reference information are allocated near each other. Streams recorded in the recording medium should be read sequentially at the normal speed in order to read the AV content data from the recording medium in succession at the normal speed. However, for special modes of reproduction such as fast-forward reproduction, jump reproduction and the like, streams recorded in the recording medium should be read at a high speed and the reference information be analyzed to locate a play-start point or to generate and pre-hold a list of reference information for the special modes of reproduction.
When MP4 is used, reference information on the entire recording medium are collectively recorded in one place. So, the reference information can be read first and held in a memory in a player. Thus, a play-start position can easily be figured out from the information in the memory, and reproduction can be done in special modes such as fast-forward reproduction, jump reproduction and the like than according to MPEG-2PS. However, since reference information is increased with an increased total time for AV content data, the memory should have a larger storage capacity.
Patent document 1:                Japanese Patent No. 3240017        
Non-patent document 1:                Home page Hi-MD of the Sony Corporation. [retrieved on Jun. 18, 2004],        Internet <URL:http://www dot sony dot co dot jp/Products/Hi-MD/>        